transmssion, dog on first and second, interested?

[elise/europa]

Next winter, I want to dismount my transmission and design a kit including 2 gears, and the slider dog to be able to remove the synchro on first and second gear, since my synchro is alreadu wear out on second (abusing track use).

I want to design a basic kit, just 2 gears to replace the existing one, same ratio, same teeth, same angle, to avoid the trouble to change the main shaft.

The question is quite simple, somebody here are interested by that solution? Whatever what, I will design it, and install it, no regard of the cost if it is lower than 2500$. But, if the gear kit are build for a quantity of 5, the price per each will decrease a lot, maybe the cost will go down to a maximum of 1000$ each. I don't want to have direct profit, but decrease the cost of my gearset for me.

For your information, I am a senior mechanical engineer, working of design, and I am doing my transmission work my-self. I have access to a very good machine shop here. If somebody want to have the transmission assemble, my brother is having a garage, and he is doing that kind of job, but he is located in Montreal Canada, the garage name is Coventry, specialised on british car. The labor is very small to dismount and re-assemble a transmission itself.

Why waiting for next winter, because I don't have access to a transmission, except mine, which it is onside the car.

Advantage:
- No synchro on first and second = paradize
- Still not noisy on street
- Minimum expense
- Very easy shift first and second

Disadvantage:
- Same ratio
- No synchro on street
- No change on the very bad ratio of the fifth gear, which is just stupid
- Perception of gear gap on first and small (in fact, the loose is coming from the dog, not from the gear)

For your information:
The kit from C-one is still using synchro, it is only a very short ratio 1 to 5, and long overdrive 6.
The kit offered by Quaife is not available at the moment, fully dog engagement, expensive, very very short ratio, like 210 km/h on six, too short for race track in Canada, and just very too short on street.

Please let me know your interest.

[ZAMMY1]

can't you just remove the blockers from the 1-2 synchronisers?
i've had numerous trannys apart but that seems to be the end result of your project.
or, do you think you really get that much more from the "dog" type engagement?
motorcycles use that type.
or is this a 'technical exercise'?
this is not a flame, i'm here to learn.
sam

[elise/europa]

ZammY,

It is not a technical exercise, it is quite funny to see your comment.

I don't know what you are calling the blockers exactly, I will assume that it is the parts moving with the fork. The synchro is a brass cup used as a clutch to adjust the speed of the gear with the shaft (and the blockers if you say so). In racing application, on quick shift, and mostly on quick unshifting, the the synchro have tendance to wera-out quickly. With a synchro mesh gear set, the teeth taking the load from the blockers to the gear don't have gap, very precise engagement, and not a lot of room for engagement when if they are turning exactly at the same speed.

The dog concept is sligthly different, it is not synchro or clutch to adjust the speed. This is one thing, but to acheive that, the teeth between the gear and the blocker have big clearance for matching. Typically, it is only 3 to 6 big teeth, in this case, probably it should be 6 since the gear diameter is quite large. The gear is typically like a female, and the blocker like a male, and the gap between both can be like 15-30 degrees for easy engagement.

All real racing transmission are using dog engagement, because it is reliable. In practice, also, it shift more easily, because you are not forcing the synchro, you are only pushing teh ball and spring for the fork lock position.

I have this set-up on my Lotus Europa, no synchro on first and two, and sycnhro on 3 to 5. It is a lovely transmission, and not wear out.

Like I said, the trouble without synchro, you need to synchronise yourself the speed of the gear when you down shift, typically, you need to play with the gas when you brake and downshift. During shifting, you will not notice the difference a lot, just easier shift.

On street, sometime, you need to do like a double clutch to engage the first, in fact, you don't need to press two times, but sometime, only sligthly release the clutch to engage to speed up the shaft, engage, and press down again. For me it is not a big trouble at all, for my mother, it is something else.

Technical exercice, for me no, I really have this trouble with my transmission, OK, I am abusing the transmission in the race track, but I am driving quite fast, and I am pushing very hard on the brake, and this don't allow me a lot of time to downshift.

If you are not taking your car on the race track, use the synchro, it is better on street.

Regards

Marc J

[kverges]

Problem is I never use 1st on the track. The one and only 1-2 shift occcurs as I leave the pit. A true dog box for 2-3-4-5 might be interesting, but not interesting enough to spend what I think it would cost.

[Thomasio]

I'm curious, are you heel-toe shifting on the track?

Thomas

[elise/europa]

Yes I am reving the engine when I downshift during braking.

Kverges, in Eastern Canada, we have two track where we go down to first, Shannonville, and St-Eustache, on very slow curve. But, I don't have trouble with my first gear at the moment, I have only trouble with the second gear, which I use a lot, and more since the engine don't have torque at low rpm. I am downshifting very often from 3 to 2.

Ideally, I will appreaciate to have no synchro on 3 and 4, but it is more expensive, and it is less required since the ratio are closer and closer at higher gear.

Anyway, I am looking for interest.

[xtn]

A very interesting project, but not something I would be interested in.

[MikeW]

Just some food for thought. Since you're likely wearing out the 2nd gear synchro, You may want to consider modifying the existing design. I wish I had the parts loose to look at for you. Anyway, other more pricey transmissions use
better synchornizers. Some are dual cone, even triple cone. I've seen some syncho rings with friction material lining the inside. Carbon is often used. Likely you can get more coeffieient of friction VS brass rings. You might look into having a steel synchro ring with a friction lining made up. You might even sell a few. The cone shaped contact surface of the gear where the ring rides can be casidian (spelling) coated. The hardness approaches diamonds. I suggest buyings a stock synchro ring and studying it. The oil has to have a way to get out to to avoid "hydoplaning". I used to put a slot in brass rings with a jewelers file on old GM trannies. As a side note, my 2nd gear synchro died also. I was rather disappointed. This seems somewhat typical with the C60/C64 trans. Keep the clutch disc light as reasonably possible. More mass to accelerate/decelerate means more synchro wear.

[elise/europa]

MikeW,

Honestly, I just did not think about improving the synchro... we call that paradigm... You have good point. I know that no synchro is an easy but expensive solution. But for me, it is more easy to design, because it is only a design issue, and no test required, and I have a dog transmission at home to based the design regarding the required gap. To play into the synchro, it is a question of testing, testing, and testing. I did not remove yet the transmission from the Elise, but it is probably more than only few hours to remove and put it back... But I will think about that.

I read somewhere that the synchro was a dual cone, but I did not see it.

Regards

[ZAMMY1]

as i said in my first post, i DO understand the difference between synchros and dog type trannys.
i was not certain of your depth of intent, hence the question of technical exercise.
i know there are gear/transmission makers for racing applications that will take nearly anything you can throw at them, and they ARE dog types.

a question in my mind, where is there a gear shop with the expertise to do the replacement parts? i have no doubt that there is someone out there but that kind doesn't come cheap or even reasonable, especially a short run of the (probably) three piece sets.

the problems i've had with steel mill gearboxes throws light in the scarcity of real help in that area. maybe there's more capability for small stuff as we'd find in the elise/corolla tranny.

anyhow, good luck, i'll be an interested bystander.
my best, sam

[MikeW]

Since you may be doing a one of a kind, you might consider machining the cone on the gear and making an adapter with the dog teeth to it. The dogs could be machined on a separate sleeve and welded to the gear. It would save having a gear made up. I know the Rockwell is high on the gear but it could be ground perhaps. Or perhaps leave the cone there and taper the ID of the dog apapter. The dog adapter could be laser cut to rough it out. And it could be fairly inexpensive. You could make several once the CAD is done. Can't help much with the slider and hub, maybe something from a Hewland could get you started, at least with a slider maybe. You might give Webster a shot about the whole thing. They're small time and may be willing to talk to the little guy. And I've thought about dogs too. Any more gearbox trouble and I'll be inside it myself.

[elise/europa]

I have the gear on hand, I will assemble the transmission tomorow, and try the car in the next two weeks.

here is the picture of the gear.

Will keep you posted.

[MikeW]

Looks like you're on the right track! Has this been expensive so far? Hope this cures the problem.

[elise/europa]

MikeW,

The delay was long since it is only a production run of 1 unit... was not the priority of the machine shop. Expensive? around 1600$ CDN, if you compare with C-one gear kit, it is expensive, but the C-one kit gear ratio was not what I need, and still with synchro. Compared with the Quaiffe kit, not too bad, and again, the Quaife gear ratio was not fitting my needs.

I copied the design on my Europa close ratio gearbox, which it work nicely.

regards
In fact, I like the stock ratio except fot the fifth gear, which is now changed, another 500$ over the kit to remove the synchro.

I assembled the transmission today, everything look fine. I am very happy.

[elise/europa]

I just try the car today, and wow, the set-up is better than expected. The shifting and downshifting are very easy (better than my Europa dog box), and quick.

No synchro issue for me in second gear this summer. Very happy. Expensive fix, but it solve the trouble.

[MikeW]

Glad to hear it works well! Nice job. Now you can drive without worrying about the short life of the synchro. Do you have to double clutch to downshift?

[elise/europa]

MikeW,

In fact, it is never required to double clutch, it is like a transmission with synchro except:

- don't spend time on neutral, go to the speed right away, like 3 to 2, 2 to 1 or 1 to 2. On race track, not a big deal, but on street, when you are relax, not very cool...
- when you start, sometime the first gear don't want to engage, just release sligthly the clutch, and push the shifter, and it goes. In real life, not a big deal.
- The effort on shifter is less on first and second since it is only one ball and spring to push inside the transmission, instead than the ball and spring, plus 3 spring and cam on the synchro.
- The shifting and downshifting is as fast as your arm...
- The transmission have a gap built-in like a motorbike (same concept, same result), because it is a 30 degrees free rotation, it is clear on the picture.

Regards

Marc

[MikeW]

Thanks Marc.

[DS1Motorsports]

How has wear been on this set-up?

[fpitas]

This is interesting, but what the heck is it doing in the ECU sub-forum?